The new diphosphanylphosphido complexes of tungsten(VI) and molybdenum(VI). Their synthesis, structures and properties

We report on the reactivity of R2P-P(Li)-PR'(2) (R = tBu, iPr, R' = NEt2, iPr) towards diimido complexes [(dippN)(2)MCl2 center dot dme] (M = Mo, W and dipp = 2,6-iPr(2)C(6)H(3)). A series of new complexes with diphosphanyl-phosphido ligands R2P-P-PR'(2) were isolated. The solid-state structures of [(dippN)(2)M(Cl)(1,2-eta-iPr(2)P-P-PiPr(2))] (2Mo and 2W) and [(dippN) 2M(Cl){1,2-eta-tBu(2)P-P-P(NEt2)(2)}] (3Mo and 3W) were established by single-crystal X-ray diffraction analysis and indicate a side-on geometry of the R2P-P-PR'(2) moiety. 3W and 3Mo are the first triphosphorus complexes with the amido ligand NEt2 on the P atom. [(dippN)(2)M(Cl) (1,2-eta-tBu(2)P-P-PtBu2)] (1Mo and 1W) and 3Mo and 3W display similar side-on geometry in solution and in the solid state. By contrast, 2Mo and 2W reveal a dynamic behavior in solution. For the first time, the reactivity of diphosphanylphosphido complexes towards different nucleophiles was studied. The complexes react with the phosphorus nucleophile Ph2PLi, yielding phosphanylphosphinidene complexes [(dippN)(2)M(Cl)(eta(2)-P-PR2)](-) Li+ (M = Mo, W) together with related diphosphanes R'P-2-PPh2. Carbon nucleophile MeLi does not yield [(dippN)(2)M(Cl)(eta(2)-P-PR2)](-) Li+ but substitutes a Cl ligand at the metal center. Moreover, we compare the coordination of the R2P-P-PR'(2) moiety to different metal centers based on DFT methods.